Studies on pyrazolo(3,4-d)pyrimidine derivatives. III. On the reaction of 1-methyl- and 1-phenyl-4-chloro-1H-pyrazolo(3,4-d)-pyrimidine with carbanion (author's transl)

Abstract

In order to introduce a carbon chain into the 4-position of 1-substituted 1H-pyrazolo-[3, 4-d]pyrimidine, substitution reactions were carried out with 4-chloro-1-methyl-(Im) and 4-chloro-1-phenyl-1H-pyrazolo[3, 4-d]pyrimidine (Ip) with a carbanion. The carbanion sources used were malononitrile, ethyl cyanoacetate, phenylacetonitrile, ethyl acetoace-tate, diethyl malonate, acetone, 2-butanone, 2-pentanone, acetophenone, propiophenone, cyclopentanone, cyclohexanone, and 1, 3-diphenyl-2-propanone. Reaction of I with malononitrile, in the presence of sodium amide, gave 1-methyl(or phenyl)-1H-pyrazolo[3, 4-d]pyrimidine-4-malononitrile (II-1), while the reaction of I with ethyl cyanoacetate, phenylacetonitrile, or diethyl malonate gave the corresponding derivatives (II-2, -3, -5). In the reaction of I with ethyl acetoacetate, the deacetylated product, ethyl 1-methyl(or phenyl)-1H-pyrazolo[3, 4-d]pyrimidine-4-acetate (II-4) was formed. Reaction of Ip with the ketones gave (1-phenyl-1H-pyrazolo[3, 4-d]pyrimidin-4-yl)methyl alkyl ketones (IIp-6 to-13). Tautomerism of the compounds (II) obtained by the present reaction was discussed from infrared, ultraviolet, and nuclear magnetic resonance spectral data.